Abstract The neutron star binary SAX J1747.0-2853, located in the Galactic Center
region at about 0.5 deg from Sgr A* and at a distance of ~9 kpc,
has been observed in outburst four times (1998, 1999, 2000 and 2001)
by BeppoSAX and RossiXTE.
At the time of its discovery in 1998 the source was observed in a low/hard state,
showing a hard tail with a high energy cutoff of ~70 keV. About two
years later the source reappeared about one order of magnitude brighter in
the X-rays (0.5-10 keV) and with a significantly steeper spectrum.
As was the case for the low state, the data could be fitted by an input model
based on two continuum primary components:
a) a soft thermal excess, which is
~4 times more luminous than the one found in hard state; b) a
non-thermal component which is compatible with either a power-law or a
comptonization spectrum. The soft component
is equally well described by pure blackbody or multi-color disk emission,
with significantly higher temperature than observed in low state
(~1.3 vs. the ~0.5 keV assuming pure blackbody).
For this model, the flux of the non-thermal component below ~10 keV is
a significant fraction of the total X-ray flux, i.e. greater than ~50%
in the 2-10 keV band.